Google Android Tutorial

We will be following exactly same procedure for all our demos. We will hereafter, see xml file and java files only, for the various demos. After a few more demos, it will be enough if I give the imports, declaration, definition and event handler.

The Android SDK comes with a number of sample applications. Within the APIDemos folder, we have a folder named 'Views'. I read it as 'GUI'. It deals with layouts and controls and animations etc. There are a lot of demos. It may be confusing at first. Though, we may like to modify and simplify the code later, it is instructive to try each one of the sample programs by clicking on 'apidemos' button in the emulator screen and getting familiarity . I will list and give a brief comment on these, later.

Demo 2 - Spinner

As usual, the standard widgets are label(textview), textbox(edittext), combo(spinner), check, radio, ticker etc. I will now give a  demo for spinner. I have provided a spinner, button and a text to display the selected item in edittext.

We can design our layout as before using DroidDraw and get the following main.xml.

(obtained by using DroidDraw).

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout android:id="@+id/widget0" 
    android:layout_width="fill_parent" 
     android:layout_height="fill_parent" 
      xmlns:android="http://schemas.android.com/ apk/res/android">                                            
<Spinner  android:id="@+id/spinner1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_x="70px" android:layout_y="42px">                                            
</Spinner>
<Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="confirm" android:layout_x="70px" android:layout_y="112px">                                           </Button>                                   
<EditText android:id="@+id/text1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="EditText" android:textSize="18sp" android:layout_x="70px" android:layout_y="182px">
</EditText>
</AbsoluteLayout>

The corresponding java source file is given below.

package  mypack.mydemos;      

import android.app.Activity;                   
import android.os.Bundle;                      
import android.widget.*;   
import android.view.View;

public class  demo extends Activity            
{                                                     
        Spinner   spinner1;
        Button    button1;           
        EditText   text1; 

      @Override                                                
      protected void onCreate(Bundle icicle)  

      {       
               	super.onCreate(icicle);                           
               	setTheme(android.R.style.Theme_Dark);
               	setContentView(R.layout.main);   
	spinner1 = (Spinner) 
 	findViewById  (R.id.spinner1);  
	button1    = (Button);
	findViewById (R.id.button1);                                               
	text1      = (EditText) 
	findViewById  (R.id.text1);       
	ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, array);        
	adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_ item);                   
	spinner1.setAdapter(adapter);         
	button1.setOnClickListener(  new clicker());    
   }         

         private static final String[] array = {        "sunday", "monday", "tuesday", "wednesday",
				         "thursday", "friday", "saturday" };  

class  clicker implements  Button.OnClickListener

{ 
	public   void  onClick(View   v)
              {        
	       String       s = (String) spinner1.getSelectedItem(); 
	         text1.setText(s);                                
	}                                         

}   


}

As before place demo.java in d:\android\tools\demo\src\mypack\mydemos. Place main.xml in d:\android\tools\demo\res\layout

Build using ant. Deploy demo.apk to the emulator exactly as in previous demo. The original demo gets overwritten. But, our work folder , where we have our xml and java files is d:\android\mydemos\ex1.They  are intact. So, no problem..The current java and xml files are in d:\android\mydemos\ex2.

When we click on the spinner, we get the items displayed as drop-down. We select an item and confirm. The selected item appears in text1. I am not going to explain the code. It is simple enough, if we remember our core java.